Jugular femoral vena cava filter system

ABSTRACT

An embolus filter introducer system has a symmetric introducer sheath with a filter inside. The introducer sheath can be attached at either end to a deployment actuator. The deployment actuator can thereby be used to push the filter out of the introducer sheath. Since the sheath can be oriented in a selectable direction, so can the filter, allowing the sheath to be introduced via a jugular or femoral approach to the vena cava.

PRIORITY DATA AND INCORPORATION BY REFERENCE

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 60/870,498, filed Dec. 18, 2006, which isincorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to a filter device that can be placed via anintroducer sheath delivery system in a vessel of a mammalian body toreduce the risk of embolisms. The invention further relates to featuresthat allow the same filter and introducer sheath assembly to be used todeploy a filter from a jugular or femoral access. Further featurespermit the filter to be pre-sealed within a reorientable deliveryintroducer sheath.

BACKGROUND ART

Inferior vena cava filters, also called IVC filters or Greenfieldfilters, are medical devices that are implanted into the inferior venacava to prevent pulmonary emboli. They work by trapping emboli whilestill permitting the flow of blood, thereby preventing an embolus fromsealing off a vessel. IVC filters are used if anticoagulation isineffective or contraindicated.

IVC filters are inserted via the blood vessels (i.e., placedendovascularly). Known filters can be compressed into thin introducersheaths permitting access to the venous system via the femoral vein orthe internal jugular vein. An introducer sheath is guided into the IVCusing fluoroscopic guidance. The filter is pushed through the introducersheath and deployed into the desired location. IVC filters are usuallypositioned just below the junction of the IVC and the lowest renal vein.

A variety of different kinds of filter designs are known. Some of theseare symmetrical and can be delivered through both jugular and femoralaccesses. The following are some examples.

US Patent Publication No. 2003/0060843 shows a filter which has anumbrella-like structure to capture emboli with struts that connect thefilter to a catheter which has a capsule on its end to hold the filterin a collapsed configuration. The catheter and capsule remain in placewhile the filter is in use so no vessel wall-holding features arerequired. The filter readily collapses as it is drawn into the capsulesince there are no extensions to get in the way.

U.S. Pat. No. 6,793,665 and US Patent Publication No. 2005/0080447 showa filter with one or more meandering filaments that define aself-expanding structure that can be drawn into a catheter. The pressureof the meandering filament(s) against the vessel wall prevents thefilter from migrating. In one embodiment, the filter is symmetrical andcan be placed through a jugular or femoral access.

US Patent Publication No. 2005/0288703 shows a filter with a capturepart with obliquely extending struts stemming from a hub which isattached at the strut endpoints to a series of V-shaped extensions thatare displaced in a flow direction from the ends of the struts. The endsof the extensions have sharp tips that engage the vessel wall to preventmovement.

US Patent Publication No. 2006/0041271 shows a filter with a cover thatcan be placed through a catheter. The filter is self-expanding from acompressed shape that is assumed by it when it is inside the catheter. Acover over those portions of the filter that would otherwise contact thevessel wall reduces pressure on the wall. The cover also helps to resistincorporation of the filter into the vessel wall by endothelialization.Oppositely-directed tips engage the wall to prevent movement.

U.S. Pat. No. 5,370,657 shows a filter in which two self-expandingcorolla elements are interlaced in opposite directions. At the center ofeach corolla is a hook that can be approached from opposite ends byloops that engage each hook to pull the corollas apart. The corollas areheld together by a resilient element that breaks when the two corollasare pulled apart, allowing each corolla to be drawn into, and collapsedwithin, a sheath for retrieval.

U.S. Pat. Nos. 5,836,969 and 6,126,673 show a filter with multiplecorollas that can assume a very small size when compressed within acatheter before deploying. The filter is made of filter-wires thatextend generally upstream from a central region of connection, free endsthat engage the vessel wall.

U.S. Pat. No. 6,273,901 and 6,589,266 show a filter that is similar tothat of U.S. Pat. No. 5,370,657, but the wires making up the corollasfollow much more complex trajectories. Also, an embodiment with hooks onthe corolla hubs is shown, but they are not explained in the patent.

U.S. Pat. No. 7,018,401 shows a filter with oppositely-directed domeportions that can have hooks at the tops of their domes. The patent saysthe hooks can be used for retrieval. The domes are flexible.

There may be various reasons for preferring asymmetric filter designsover symmetric ones. The latter tend to be longer, for instance. It ispossible the sizes of the introducer sheaths may need to be longer,depending on the particular design. Filters are generally prepackaged inthe introducer sheath for at least two reasons. The first is that it isdesirable for filters to be highly compressed to fit into a thinintroducer sheath, which is a difficult task to perform so it is usuallydone under controlled conditions as a final step in manufacturing. Thus,filters are delivered pre-fitted within the introducer sheath. Thesecond reason filters are pre-installed in the introducer sheath is forsterility. Sealed and sterilized while within the introducer sheath, therisk of contamination is greatly reduced. It is desirable for a filterof asymmetric design to be deliverable through femoral and jugularaccesses without the need for separate delivery systems.

DISCLOSURE OF INVENTION

Briefly, An embolus filter introducer system has a symmetric introducersheath with a filter inside. The introducer sheath can be attached ateither end to a deployment actuator. The deployment actuator can therebybe used to push the filter out of the introducer sheath. Since thesheath can be oriented in a selectable direction, so can the filter,allowing the sheath to be introduced via a jugular or femoral approachto the vena cava.

An embodiment of a jugular-femoral filter delivery system has areversible introducer sheath that contains a filter of asymmetricdesign. That is, the filter has a cranial end which is intended to beoriented in a cranial direction and a caudal end which is intended to beoriented in a caudal direction. The reversible introducer sheathcontains a filter and connects to a delivery device at selectableopposite ends thereof This permits the filter to be pushed out eitherend of the introducer sheath. Engagement portions of the filter may beretained by a spline cap that keeps the engagement elements fromimpeding movement of the filter through the introducer sheath. In anembodiment, the engagement elements are legs with hooks at their ends.

The spline cap is guided by slides that run from one end of theintroducer sheath to the other. Abutments on both ends of the introducersheath prevent loss of the spline cap into the body during deployment.The filter is loaded with the legs in the spline cap. The spline cap ismoveable, so it will be positioned on the jugular side of the sheathwith the filter legs retained by it. The introducer sheath will then beconnected via snap-fit to a pusher assembly. A pusher which is almostthe size of the spline cap is advanced through the introducer sheath sothat is pushes the filter out of the introducer sheath. In the femoralapproach, the hooks bend until the filter is released from the splinecap. In the jugular approach, the hooks are pushed beyond the splinecap. In either case, the spline cap is retained within the reversibleintroducer sheath by abutments at the ends of the sheath.

According to an embodiment, an embolus filter delivery device has apusher assembly with a frame and a pusher member movable with respect tothe frame. An introducer sheath has an embolus filter housed therein.The introducer sheath has engagement portions on either end thereofEither of the introducer sheath engagement portions is connectable tothe pusher assembly frame to allow the pusher member to move into theintroducer sheath and push the filter out of it and such that the filtercan be pushed out of the introducer sheath in either of two oppositedirections.

Preferably, in the foregoing embodiment, the introducer sheathengagement portions and the pusher assembly frame are configured toprovide a snap-fit connection between them to hold the introducer sheathto the pusher assembly. The introducer sheath preferably has a lengththat is sufficient to extend from a femoral access to a vena cava of ahuman.

The introducer sheath can have a length that is sufficient to extendfrom a jugular access to a vena cava of a human. Alternatively, theintroducer sheath can extend only part of the length required with thepusher assembly making up the difference. The total length is preferablysufficient to extend from a standard femoral access of a human to thevena cava and the from a standard jugular access to the vena cava.

The embodiment is suited to a filter that has a longitudinal axis andwhich filter has an asymmetric shape with respect to the longitudinalaxis. The filter would generally be oriented with respect to its cranialend and its caudal end when in position. The filter is configured to bepushed from either end by the pusher member. The filter may haveengagement elements that are held by a spline cap. The spline cap ispreferably slidable within the introducer sheath. The introducer sheathpreferably has an internal surface with protruding portions that centerthe spline cap therewithin. Thus, the spline cap being centered canthereby prevent the engagement element ends from contacting the internalsurface. This can ensure the filter can be pushed along the introducersheath. Preferably, the introducer sheath is sealed by removable sealsat either end of the introducer sheath.

The filter may have a hub and at least one corolla with axially andradially extending elements extending from the hub. The filter may haveends that are oriented such that one end is aimed in the cranialdirection when deployed in a vena cava and the other is aimed in thecaudal direction when deployed in a vena cava.

According to another embodiment, a method of delivering an embolusfilter includes: choosing a jugular or femoral approach to place anembolus filter in a living host and deploying a filter using anintroducer sheath oriented, with respect to a living host, in adirection corresponding to the chosen of the jugular or femoralapproach. The deploying may include attaching an introducer sheath,which contains the embolus filter, to a deployment actuator at an endthat corresponds to the chosen approach, the deployment actuator beingused to push the filter out of the introducer sheath to deploy thefilter. The introducer sheath may be attachable at either end to adeployment actuator and insertable into a living host at either end.

The deploying may further include attaching an introducer sheath, whichcontains the embolus filter, to a deployment actuator at an end thatcorresponds to the chosen approach, and inserting the introducer sheathinto a living host beginning at the end of the introducer sheathopposite the end corresponding to the chosen approach, whereby thefilter is oriented relative to the living host. Preferably, thedeploying includes pushing the filter out of the introducer sheath.

The method may further include orienting the introducer sheath withrespect to a deployment device and attaching it in one of two possibleways, each corresponding to a respective one of the femoral and jugularapproaches.

In another embodiment, a sheath with first and second ends sealed atboth ends with a vena cava filter within it. The filter and interior ofthe sheath are sterilized. The sheath is packaged with a deliverymechanism that can be attached to either end of the sheath to allow thefilter to be deployed from the opposite end of the sheath by insertingthe opposite end into a corresponding one of a jugular and venousaccess. The filter has a cranial end that is aligned with the sheathand, when deployed, must face the cranial end of the vena cava. Thus,choosing the end of the sheath to attach to the deployment mechanism andinserting the sheath via the opposite end, causes the filter to beinserted into the vena cava with a chosen orientation. In this way, thefilter can always be placed with the filter cranial end facing the venacava cranial end.

In yet another embodiment, a sheath for connection to a deploymentactuator for introducing a filter. The sheath includes a tubular memberhaving a first end and a second end. The tubular member includes aninner surface defining an interior space between the first and secondends for housing the filter. The sheath further includes first means forengaging a pusher assembly to provide for introduction of the filterfrom the second end and second means for engaging a pusher assembly toprovide for introduction of the filter from the first end.

In any of the foregoing embodiments having a spline cap, the spline capmay have grooves that face radially outward. The filter engagementelements may be held by the spline cap while the spline cap grooves areheld by protrusions on the inside of the introducer sheath. Thisprevents the spline cap from rotating, thereby preventing the legs fromtwisting.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary embodiments of theinvention, and, together with the general description given above andthe detailed description given below, serve to explain the features ofthe invention.

FIG. 1 shows an example of a filter of asymmetric design according tothe prior art.

FIG. 2 shows the placement process of the filter of FIG. 1 using afemoral and a jugular approach according to the prior art.

FIG. 3 shows a filter fitted in a reversible introducer sheath.

FIGS. 4A and 4B show cross-section of a portion of the structure in FIG.3 illustrating the location and function of the spline cap according totwo respective embodiments, one having a spline cap with no grooves andthe other having grooves to engage ridges in the introducer sheath toprevent rotation of the spline cap and thereby to prevent twisting ofthe legs.

FIGS. 5A and 5B show alternative mating configurations of a reversibleintroducer sheath and a pusher assembly.

FIG. 6 shows an alternative fitting assembly in which the ends of aintroducer sheath have different sizes.

MODE(S) OF CARRYING OUT THE INVENTION

An illustrative embodiment of a vena cava filter is shown and describedin U.S. Pat. Nos. 6,258,026 for “Removable embolus blood clot filter andfilter delivery unit” and U.S. Pat. No. 6,007,558 for “Removable embolusblood clot filter ;” both of which are hereby incorporated by referencein their entireties herein. A similar vena cava filter is shown at 100in FIGS. 1 and 2.

Referring to FIGS. 1 and 2, the filter 100 is shown in an expandedstate. Preferably, the filter is made of metal wires forming extensionelements 105, 110 and held together by a hub 102 where they are joined,for example, by plasma welding. The wires are preferably made of shapememory alloy with a martensite phase that allows the wires to bestraightened so as to enable insertion in a catheter and deploymenttherefrom. In the austenitic phase, the filter recovers to its expandedstate, which is illustrated. Other details relating to the design can befound in the documents incorporated by reference above.

The filter 100 preferably has a double basket design with firstextension elements 105 forming one basket and second extension elements110 forming a second basket. Both the first extension elements 105 andsecond extension elements 110 engage the walls of the vena cava 107after deployment. The second extension elements 110 preferably havehooked ends 115 that penetrate the vena cava 107 wall and prevent thefilter 100 from moving downstream due to the frictional force of bloodmoving past it. As described in the above incorporated documents,preferably, the hooked ends 115 are configured to yield upon theapplication of a specified amount of force to ameliorate retrieval.

The filter 100 may be delivered by femoral or jugular access asillustrated by the introducer sheaths in FIG. 2, showing alternatively asheath 150J in a jugular approach and a sheath 150F in a femoralapproach. When the jugular approach is used, the filter 100 is pushedfrom the introducer sheath 150J with the basket concavity first and thehub 102 last. When the femoral approach is used, the filter 100 ispushed from the introducer sheath 150F with the basket concavity lastand the hub 102 first. Accordingly, a different orientation of thefilter 100 within the introducer sheath is required depending upon theapproach. Prior to the inventor's development, two types of introducersheaths 150J, 150F were required where the filter 100 was pre-sealedwithin the introducer sheath 150J, 150F in order to provide a sheath foreach type of approach: (i) a sheath 150J and filter oriented for ajugular approach and (ii) a sheath 150F and filter oriented for thefemoral approach.

To reduce or otherwise eliminate the need for two types of introductionsheaths, the inventor has developed a single introducer sheath, with apreferably pre-installed filter, that can be used in either a jugular ora femoral approach. FIG. 3 shows an illustrative filter 100A loaded intoan introducer sheath 200 having a preferred symmetric design tofacilitate either a jugular or femoral approach. The introducer sheath200 is a preferably tubular member having opposed ends 202. The tubularmember 200 has an inner surface 219 defining an interior space forhousing the filter 100. The ends 202 of the sheath 200 are preferablyidentical. Accordingly, only one end 202 is shown. The sheath end 202 isshown mated with the end of a pusher assembly 212 (also shown at 325 inFIGS. 5A and 5B discussed below) or other deployment actuator. Theintroducer sheath end 202 has a preferably snap fit protrusion 210 thatengages a recess 220 with an edge 222 to seal and hold the introducersheath 200 in the pusher assembly. Because of the symmetrical andpreferably identical design of the introducer sheath ends 202, thesheath 200 can be reversed or interchangeable coupled at its ends 202 toa pusher assembly to appropriately orient the filter 100 for either afemoral or a jugular approach.

The introducer sheath 200 further preferably includes abutments 216 atits ends to prevent a spline cap 250, disposed about the extensionelements of the filter 100, from moving beyond the ends 202 of theintroducer sheath 200. The spline cap 250 maintains the extensionelements of the filter in a radially collapsed configuration within thesheath 200 in order to minimize or eliminate frictional engagementbetween the interior surface of the sheath 200 and the filter 100.

Referring to both FIGS. 3 and 4A, the spline cap 250 preferably has agenerally cylindrical shape dimensioned so as to slide within theinterior of the sheath 200. The interior surface of the introducersheath 200 preferably includes one or more projections or rails 218 toengage and guide the spline cap 250 along the axial length of the sheath200. More specifically, the spline cap 250 is guided by the rails 218which further preferably center the spline cap 250 in spaced relation tomost of the inner surface 219 of the introducer sheath 200. The spacingprovides room for hooks 244 on the filter 100A. The hooks 244 are shownin section at 252 (only one is labeled, although six are shown). Thefilter 100A extension elements or legs 256 wrap around the spline cap250 ending in the hooks 25 2. Recesses 254 may be formed in the splinecap 250 to hold the legs 256 in position with respect to it, the legs256 being held by spring tension. FIG. 4B shows a cross-section of analternate embodiment of the spline cap 251. Spline cap 251 preferablyhas grooves 221 that engage the rails 218 of the introducer sheath 200to prevent the spline cap 251 from rotating. This in turn preventstwisting of the legs 256 of the filter 100.

Referring now to FIGS. 5A and 5B, to use the filter delivery system fora femoral approach, the introducer sheath 200 is connected to the pusherassembly 325 at a femoral end 300F such that the hub 102 is introducedfirst from the sheath. To use the filter delivery system for a jugularapproach, the introducer sheath 200 is connected to the pusher assembly325 at a jugular end 300F such that the extension elements of the filter100 are introduced first. To facilitate the connection of the introducersheath 200 to the pusher assembly 325, a bevel 224 may be provided atthe ends 300F and 300J of the introducer sheath 200. The pusher assembly325 seals to the femoral end 300F by locking to it. The introducersheath 200 has a length that is preferably sufficient to extend from theaccess to the delivery location in either a femoral or jugular approach.The pusher assembly 325 may have a dilator as indicated figuratively at333. A pusher 315 at the end of a shaft 320 is pushed through the pusherassembly 325 by a suitable manually-operated or automatic mechanism.Once the introducer sheath 200 is positioned with its distal end at thedelivery site, the pusher 315 is advanced until it contacts the filter.The pusher 315 is finally pushed until the filter 100A is deployed.Preferably, removable seals are provided on the ends 300J and 300F ofthe introducer sheath 250 such that the introducer sheath houses andencloses the filter 100A in a sterile condition until the seals areremoved in preparation for filter delivery. Note that the introducersheath 250 can be made shorter than the length required to extend fromthe access to the vena cava if the deployment actuator is made suitablyelongate to make up the difference.

In the foregoing embodiments, the introducer sheath may be a single-usearticle that is used to store the filter until it is used. The pusherassembly may also be a single-use disposable component. In anembodiment, the pusher assembly (e.g., 325) is packaged with thereversible introducer sheath and filter described above.

In use, a clinician may first determine whether to use a femoral orjugular approach. The introducer sheath 200 is unsealed and attached tothe pusher assembly at the jugular or femoral end, according to theapproach (femoral or jugular) selected. The introducer sheath 200 isthen fed into the selected approach and the pusher assembly used to pushthe filter out of the introducer sheath.

While the introducer sheath 200 was described as being attachable to adeployment device using a snap-fit type mechanism, other types ofattachments are possible. For example, a locking ring, swage fitting,threaded attachment, or slip ring type of attachment or even frictionalengagement of mating sleeves could be used.

Also, while a particular example of a filter was shown, other kinds offilters may be used with the present delivery system. Preferably, thefilter has a cranial end and a caudal end such that the system can beadvantageously used to orient the filter simply by orienting theintroducer sheath to the access and attaching the deployment device tothe corresponding end. The engagement elements of the example filterincluded hooks which made it desirable to have a spline cap, but thespline cap may not be necessary depending on the particularconfiguration of the filter. For example, some types of engagementmechanisms will readily slide on the interior surface of the sheath. Inaddition, if hooks are provided on the filter, a circumferential jog maybe formed into the legs to provide a portion that can ride on the railsof the sheath and thereby prevent the hooks from engaging the sheathinterior surface.

In addition, while the deployment mechanism discussed above included amechanical pusher, it is possible to employ a pneumatic or hydraulicpushing device or even a pulling mechanism for deployment. For example,a suture threaded around the end of the introducer sheath and back couldbe used to pull a filter out of a suitably designed sheath. Saline fluidcould be used to flush a filter from the sheath. A piston driven by airpressure could also be used to push the filter.

While in the example embodiments of introducer sheath 200, the ends ofthe sheath 300J and 300F are configured as male fittings which arereceived by female mating fittings on the pusher assembly 325, otherembodiments are possible. For example, the introducer sheath 200 couldinstead be provided with female fittings that mate with a male fittingon the pusher assembly 325. Also, the nature, size, and type of fittingused on the ends of the sheath 300J and 300F need not be identical inall embodiments. For example, as shown in FIG. 6, the same introducersheath could have a small-diameter end 368 and a large diameter end 366which are capable of mating to the same pusher assembly 372; thelarge-diameter end 366 fitting a large recess 371 and the small-diameterend 368 fitting a small recess 373.

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations, and changes to thedescribed embodiments are possible without departing from the sphere andscope of the present invention, as defined in the appended claims.Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

1. An embolus filter delivery device for delivering an embolus filter toa delivery site within a human living host, comprising: a) a pusherassembly having a frame and a pusher member movable with respect to theframe, the pusher assembly having a pusher assembly end portion with apusher assembly connector; b) an introducer sheath having an inner lumenand that is configured to be inserted into a circulatory system of ahuman living host, said sheath having first and second opposed sheathends with an embolus filter housed in said lumen in between said sheathends, wherein one sheath end has a first sheath end connector and thesecond sheath end has a second sheath end connector, each end connectorenabling connection to the pusher assembly frame at the pusher assemblyconnector; c) wherein either of said first and second sheath endconnectors is selectively connectable to the pusher assembly connector;d) a connection of the pusher assembly to a selected sheath end enablingthe pusher member to push the filter out of the other sheath end; e)wherein each sheath end is sized and shaped to be insertable into thecirculatory system of the human living host; and f) wherein when thepusher assembly and a selected sheath end are connected together, andthe sheath is inserted into the living host via jugular or femoralaccess, the other one of the sheath ends is a free end that defines adischarge opening into the living host's circulatory system at the venacava and enabling discharge and placement of the embolus filter at thevena cava of the living host.
 2. The device of claim 1, wherein eitherof the introducer sheath end connectors and the pusher assemblyconnector are joined with a snap-fit connection.
 3. The device of claim1, wherein the introducer sheath has a length that is sufficient toextend from a femoral access to a vena cava of a human living host. 4.The device of claim 1, wherein the introducer sheath has a length thatis sufficient to extend from a jugular access to a vena cava of a humanliving host. 5-6. (canceled)
 7. The device of claim 1, wherein thefilter is configured to be pushed from either sheath end by the pushermember.
 8. The device of claim 1, further comprising a spline cap housedwithin the introducer sheath, the filter having engagement elements thatare connected to the spline cap. 9-12. (canceled)
 13. The device ofclaim 1, wherein the filter has a hub and at least one corolla withaxially and radially extending elements extending from the hub.
 14. Thedevice of claim 1, wherein the introducer sheath is sealed by removableseals at each sheath end.
 15. The device of claim 1, wherein the filterhas filter ends that are oriented within the sheath lumen such that onefilter end is aimed in the cranial direction when deployed in a venacava and the other filter end is aimed in the caudal direction whendeployed in the vena cava. 16-21. (canceled)
 22. A vena cava filterdelivery system for delivery of the filter within the vena cava of apatient, comprising: a) a sheath having first and second cylindricallyshaped sheath ends and an interior therebetween and a vena cava filtercontained within said sheath interior, each sheath end being sealed soas to seal said vena cava filter within the interior; b) the filter andinterior of the sheath being sterilized; and c) a delivery mechanismthat can be selectively attached at a connection to either of the firstand second ends with a delivery system attachment portion; d) whereinthe sheath and contained filter are configured to be deployed into ahuman patient's circulatory system, wherein the filter can beselectively deployed from one of the first and second sheath ends, thefilter having a cranial end that is aligned with the sheath such that,when the filter is deployed, the cranial end faces the cranial end ofthe vena cava; e) wherein once connected to either of the first andsecond ends, the attachment portion and delivery mechanism are sized andshaped to be deployed into the human patient's circulatory system; andf) wherein when a pusher assembly and a selected sheath end areconnected together, and the sheath is deployed into the patient'scirculatory system, the other one of the sheath ends is a free end thatdefines a discharge opening into the patient's circulatory system at thevena cava, said free end discharge opening enabling discharge andplacement of the filter at the vena cava of the patient.
 23. (canceled)24. The system of claim 22, wherein the sheath has a length that issufficient to extend from both a jugular access to a vena cava of ahuman and to extend from a femoral access to a vena cava of a human. 25.(canceled)
 26. The device of claim 22, further comprising a spline capcontained within said sheath, the filter having engagement elements thatare held by the spline cap.
 27. The device of claim 26, wherein thespline cap is slidable within the sheath.
 28. (canceled)
 29. The deviceof claim 26, wherein the sheath has an internal surface with protrudingportions that center the spline cap therewithin, the spline cap thusbeing centered thereby preventing the engagement element ends fromcontacting the internal surface.
 30. The device of claim 29 wherein thefilter having has engagement elements with ends that are held by thespline cap, the sheath having an internal surface with protrudingportions that engage the spline cap to prevent the spline cap fromrotating, thereby preventing the legs from twisting.
 31. An embolusfilter delivery device for delivering an embolus filter to thecirculatory system of a patient next to the patient's vena cava,comprising: a) an introducer sheath with an open ended interior lumenthat contains an embolus filter therein; b) the introducer sheath havinga first sheath end with a first sheath end connector and a second sheathend with a second sheath end connectors, each sheath end having aremovable seal; c) a deployment actuator tube having a centrallongitudinal axis and an end portion with a connector that isselectively connectable to either one of said first and second sheathend connectors; d) wherein the sheath end connectors are each sized andshaped to be deployed into a human patient's circulatory system; and e)wherein when one of the sheath ends is connected to a pusher connector,and the sheath is deployed into a human patient's circulatory system,the other one of the sheath ends is a free end that includes a dischargeopening into the patient's circulatory system at the vena cava thusenabling discharge and placement of the embolus filter at the vena cavaof the patient. 32-35. (canceled)
 36. The device of claim 31, whereinthe filter has a longitudinal axis and which filter has an asymmetricshape with respect to the longitudinal axis.
 37. The device of claim 31,wherein the ends of the introducer sheath are sealed in a manner thatprevents loss of sterility of its interior lumen.
 38. The device ofclaim 31, further comprising a spline cap, the filter having engagementelements that are held by the spline cap. 39-54. (canceled)